Hexacoordinated transition metal compounds containing at least one polyfluoroalkyl substituent

ABSTRACT

Hexacoordinated transition metal compounds, useful as antiknocks, having the structure ##STR1## wherein M is a divalent metal selected from the group Mn, Fe, Co and Ni, 
     L 1  and L 2  are the same or different chelate-forming β-diketone groups having from 5 to 20 carbon atoms, one or both of L 1  and L 2  having at least one polyfluoroalkyl group, --CF 2  X, adjacent to the carbonyl group, 
     X is selected from the group H, F, Cl, phenyl, C 1  -C 6  alkyl and C n  F 2n  Y, 
     n is 1 to 6, 
     Y is H, F, or Cl, 
     L 3  is a ligand having the structure A-Z-B, 
     wherein 
     A and B are the same or different members of the group --NH 2 , --NHR 5 , --NR 5  R 6 , OH, OR 5 , SH, SR 5  and PR 5  R 6 , 
     R 5  and R 6  are the same or different members of the group C 1  to C 4  alkyl, and 
     Z is a divalent hydrocarbyl group having 2 to 10 carbon atoms selected from a member of the group alkylene, phenylene and cycloalkylene, each member providing 2 or 3 carbon atoms between A and B, with the proviso that when Z is phenylene, the number of carbon atoms between A and B is 2.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to hydrocarbon-soluble coordination compounds ofdivalent manganese, iron, cobalt, and nickel which are useful asantiknock additives in fuels.

2. Description of the Prior Art

One method for improving gasoline antiknock quality (also known asoctane quality) is by increasing therein the content of high octanehydrocarbons such as benzene, toluene and the like. This use of highoctane hydrocarbon components is relatively uneconomical since they aremore valuable as solvents and chemical feedstocks than as gasolinecomponents.

Another method for improving the antiknock quality of gasoline is to addantiknock additives. In the past, tetraalkyllead compounds have been themost popular antiknock additives. The advent of automobiles equippedwith catalytic converters has brought the attendant requirement forlead-free gasoline. Thus, there is the corresponding need to developacceptable antiknock additives to replace those containing lead.

Most lead-free antiknocks suggested in the art are commerciallyunacceptable because of one or more deficiencies such as high cost, lowantiknock activity, hydrolytic-, thermal-, or oxidative-instability,insufficient solubility in gasoline, inadequate volatility, and too-highwater solubility. Before discussing the compounds of this invention, abrief summary of some of the prior art teachings will be provided.

British Patent No. 287,192 teaches that β-diketone (such asacetylacetone) compounds of heavy metals such as Fe, Ni, Co, Cr, Th, Cu,Mn, Mo, V and W are useful antiknocks for hydrocarbon fuels. However, inspite of suggestions in the art of processes of stabilizing andsolubilizing metal β-diketonates in hydrocarbon fuels, e.g., U.S. Pat.Nos. 2,144,654 and 2,156,918, the metal β-diketonates have not been usedcommercially as antiknocks.

The utility of the above-mentioned metal β-diketonates as gasolineantiknocks is limited by their low solubility in gasolines and their lowvolatility. The divalent cobalt compound of acetylacetone,bis(acetylacetonate)Co(II), has a solubility in gasoline of less than0.025% at room temperature.

Recent studies have indicated that the acetylacetonates of Mn, Fe, Co,and Ni are polymerized (trimers and tetramers) in the solid state and innonpolar solvents. The oligomeric nature of these compounds mostprobably explains their low solubility in gasolines and their lowvolatility. See Graddon, Nature, 195, 891 (1961), "Polymerization ofTransition Metal β-Diketone Chelates"; Cotton et al, J. Am. Chem. Soc.,86, 2294 (1964) "The Tetrameric Structure of Anhydrous CrystallineCobalt (II) Acetylacetonate"; and Graddon, Coordin. Chem. Rev., 4, 1(1969), "Divalent Transition Metal β-Keto-Enolate Complexes as LewisAcids".

From the above, it might appear that a transition metal chelate ofβ-diketones which would be monomeric in hydrocarbons such as gasolinewould have the required solubility, volatility, and antiknock activity.It is known to prepare divalent transition metal chelates of β-diketoneswhich are monomeric in the solid state and in nonpolar solvents by usinga β-diketone with bulky groups to preclude self-polymerization of thechelate compounds. Thus, chelate compounds of divalent transition metalswith 2,2,6,6-tetramethyl-3,5-heptanedione (dipivaloylmethane, DPM) arereported to be monomeric in the solid state and in non-polar solvents.However, such compounds are not practical as antiknock additives becauseof their great sensitivity to air oxidation. Fe(DPM)₂, for example, isreported to "char immediately on exposure to air"; see Fackler et al,Inorg. Chem., 6, 921 (1965). Mn(DPM)₂ "charred immediately on contactwith air"; see Hammond et al, Inorg. Chem., 2, 75 (1963). Extremesensitivity of Co(DPM)₂ to oxidation is noted in the Hammond referencesupra, p. 76, and by Gerlach et al in Inorg. Chem., 8, pp. 2293 and 2294(1969).

Metal chelates with β-diketones containing substituents such as fluorineto enhance the volatility of the metal chelates have also been prepared.Haszeldine et al, J. Chem. Soc. 609 (1951), prepared uranium chelates oftrifluoroacetylacetone (TFAA) and hexafluoroacetylacetone (HFAA) whichcould be sublimed without decomposition. Morris et al, Inorg. Chem. 2411 (1963), prepared dihydrates of hexafluoroacetylacetonates of zinc,nickel, cobalt, manganese and iron, but attempts to dehydrate thesecomplexes by sublimation were unsuccessful.

Considerable work has also been done with copper chelates of fluorinatedβ-diketones primarily because of the ease of formation of the chelatecompounds which are not subject to oxidation as are those of Co⁺⁺ andFe⁺⁺. See, for example, Calvin et al J. Am. Chem. Soc. 67, 2003 (1945);Reichert et al, Canadian J. Chem. 48, 1362 (1970); Fenton et al J. Chem.Soc. 1577 (1971); and McMillin et al, J. Am. Chem. Soc. 98 3120 (1976).

Fenton et al, in J. Chem. Soc. 1577 (1971) disclose complexes ofbis(hexafluoroacetylacetonate)Copper II with some nitrogen bases andglycols. Among the bidentate nitrogen bases, are disclosedethylenediamine, N,N'- and N,N-dimethylethylenediamine,N,N,N',N'-tetramethylethylenediamine (TMED) andN,N,N',N'-tetramethyl-o-phenylenediamine. Izumi et al, in Bull. Chem.Soc. (Japan) 48 3188 (1975) disclose nitrogen base addition products ofbis(hexafluoroacetylacetonato) complexes of Co(II), Ni(II), Cu(II) andZn(II). The two disclosed bidentate nitrogen bases are1,10-phenanthroline and 2,2'-bipyridine.

The antiknock activity of the compounds described herein, particularlythat of the preferred cobalt compound, is unexpected in view of theteaching in the art that cobalt compounds are not considered to be goodantiknocks. Thus, a paper presented at the American Petroleum Institute,Division of Refining, May 14, 1971 (API preprint No. 47-71 at page 859)by Unzelman et al, stated that cobalt compounds are mild antiknocks andthat the metal compounds having maximum effectiveness are those withmetal atoms bonded to carbon.

On the contrary, the compounds described herein have no metal to carbonbonds and yet they provide effective antiknock performance. In fact, apreferred cobalt compound, as will be detailed more completely inExample 32, is more efficient by about 130% to 240% on a metal weightbasis versus a manganese compound of metal to carbon bonds and provenantiknock performance.

SUMMARY OF THE INVENTION

The compounds of this invention are hexacoordinated transition metalcomplexes having the structure ##STR2## wherein

M is a divalent metal selected from the group Mn, Fe, Co and Ni,

L₁ and L₂ are the same or different chelate-forming β-diketone groupshaving from 5 to 20 carbon atoms, one or both of L₁ and L₂ having atleast one polyfluoroalkyl group, --CF₂ X, adjacent to the carbonylgroup,

X is selected from the group H, F, Cl, phenyl, C₁ -C₆ alkyl and C_(n)F_(2n) Y,

n is 1 to 6,

Y is H, F, or Cl,

L₃ is a ligand having the structure, A-Z-B,

wherein

A and B are the same or different members of the group --NH₂, --NHR₅,--NR₅ R₆, OH, OR₅, SH, SR₅ and PR₅ R₆,

R₅ and R₆ are the same or different members of the group C₁ to C₄ alkyl,and

Z is a divalent hydrocarbyl group having 2 to 10 carbon atoms selectedfrom a member of the group alkylene, phenylene and cycloalkylene, eachmember providing 2 or 3 carbon atoms between A and B, with the provisothat when Z is phenylene, the number of carbon atoms between A and B is2.

In X, the C₁ to C₆ alkyls can be straight or branched; the C₅ and C₆alkyls can be cyclic; and C_(n) F_(2n) Y can be straight or branched. InZ, the alkylene can be straight or branched, and the phenylene andcycloalkylene can be substituted or unsubstituted.

The preferred compounds of this invention have the structure: ##STR3##wherein

M is a divalent metal selected from Mn, Fe, Co and Ni,

R₁, R₂, R₃, and R₄ are each individually selected from C₁ to C₃perfluoroalkyl and C₁ to C₆ alkyl with at least one of R₁, R₂, R₃, andR₄ being a perfluoroalkyl group, and

R₅ and R₆ are selected from hydrogen and C₁ to C₄ alkyl.

The preferred metals are Co and Ni, with Co being most preferred. Thepreferred compounds are those wherein R₁, R₂, R₃ and R₄ are each CF₃,wherein R₅ and R₆ are each CH₃, and wherein Z is --C₂ H₄ --. The mostpreferred compounds of the invention are Co(II) (HFAA)₂.TMED and Ni(II)(HFAA)₂.TMED. These preferred compounds provide outstanding stability,volatility, solubility in hydrocarbons and antiknock performance.

DETAILS OF THE INVENTION

The compounds of this invention are typically made by contacting thedivalent salt of the metal, such as the chloride, nitrate, acetate,etc., with β-diketones, L₁ and L₂, and a donor ligand, L₃, in the molarratio of 1:2:1. The reactants can be combined in an aqueous or anorganic medium in the presence of a base such as sodium hydroxide. Thereaction can be carried out under an inert atmosphere but such is notrequired. A compound with mixed β-diketone ligands can be prepared bysequential addition of the two different β-diketones to the metal salt.Thus, for example, by adding to a basic solution of cobaltous acetate amolar equivalent of acetylacetone (AA), then a molar equivalent ofhexafluoroacetylacetone (HFAA), and finally a molar equivalent ofN,N,N',N'-tetramethylethylenediamine (TMED), the following compound isobtained: Co(II) (AA) (HFAA).TMED.

The formula, Co(II) (AA) (HFAA).TMED, is a convenient shorthand methodof representing the coordination compounds of a divalent metal withβ-diketones and a diamine ligand wherein the AA is the anion ofacetylacetone, HFAA is the anion of hexafluoroacetylacetone, TMED istetramethylethylenediamine, and the Roman Numeral (II) indicates thatthe metal ion is divalent. The practice of using the initials of theparent β-ketone in the formula of the coordination compound is widelyused in the art; see, for example, the above cited Morris reference. Thediamine ligand set off in the formula by a period indicates that it isan intact diamine molecule which is coordinated to the metal ion.

The β-diketones, L₁ and L₂, suitable for the preparation of thecompounds of this invention are represented by the formula, R-C(O)-CH₂-C(O)-R', where R and R' are any C₁ to C₃ polyfluoroalkyl. Theβ-diketones are well-known in the art and can be prepared by knownmethods. Some β-diketones such as acetylacetone are availablecommercially. β-diketones with perfluoroalkyl groups are alsowell-known. Haszeldine et al, J. Chem-Soc. 609 (1951) disclose thepreparation of trifluoroacetylacetone by Claisen-type condensation ofethyltrifluoroacetate with acetone and the preparation ofhexafluoroacetylacetone by the condensation of ethyltrifluoroacetatewith trifluoroacetone.

The β-diketone ligands for the preparation of the present compounds areselected from 2,4-pentanedione, 1,1,1-trifluoro-2,4-pentanedione,1,1,1,5,5,5-hexafluoro-2,4-pentanedione, 1,1-difluoro-2,4-pentanedione,1,1,5,5-tetrafluoro-2,4-pentanedione,1-chloro-1,1-difluoro-2,4-pentanedione,1,5-dichloro-1,1,5,5-tetrafluoro-2,4-pentanedione,1-phenyl-1,1-difluoro-2,4-pentanedione, 2,4-hexanedione,2-methyl-3,4-hexanedione, 1,1,1-trifluoro-2,4-hexanedione,1,1,1,2,2-pentafluoro-3,5-hexanedione,1,1,1,2,2,6,6,6-octafluoro-3,5-hexanedione,1,1,1-trifluoro-5-methyl-2,4-hexanedione,1,1,1,6,6,6-hexafluoro-2-methyl-3,4-hexanedione,1,1-difluoro-2,4-hexanedione, 2,2-difluoro-3,5-hexanedione,1,1,2,2-tetrafluoro-3,5-hexanedione,1,1,1,5,5-pentafluoro-2,4-hexanedione,1-chloro-1,1-difluoro-2,4-hexanedione,1-chloro-1,1,2,2-tetrafluoro-3,5-hexanedione, 2-methyl-3,4-heptanedione,3,4-heptanedione, 2,6-dimethyl-3,5-heptanedione,2-methyl-4,6-heptanedione, 2,2,6,6-tetramethyl-3,5-heptanedione,1,1,1-trifluoro-2,4-heptanedione,1,1,1,2,2-pentafluoro-3,5-heptanedione,1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione,1,1,1,2,2,3,3,7,7,7-decafluoro-4,6-heptanedione,1,1,1,2-tetrafluoro-2-trifluoromethyl-6-methyl-3,5-heptanedione,1,1,1,2,6,7,7,7-octafluoro-2,6-ditrifluoromethyl-3,5-heptanedione,1,1-difluoro-2,4-heptanedione, 1-chloro-1,1-difluoro-2,4 -heptanedione,3,3-difluoro-4,6-heptanedione,1-chloro-1,1,2,2-tetrafluoro-3,5-heptanedione,1,1,2,2,6,6,7,7-octafluoro-3,5-heptanedione,1,7-dichloro-1,1,2,2,6,6,7,7-octafluoro-3,5-heptanedione,2-methyl-4,6-octanedione, 2,8-dimethyl-4,6-nonanedione, 2,4-decanedione,benzoylacetone and benzoyltrifluoroacetone.

The two β-diketone ligands used in the compounds of this invention canbe the same or different provided that at least one of the β-diketoneligands contains at least one polyfluoroalkyl group. The presence of apolyfluoroalkyl group in at least one of the β-diketone ligands isrequired for good antiknock activity. The compounds will preferablycontain perfluoroalkyl groups on both β-diketones. The most preferredcompounds are those made from β-diketones containing two perfluoroalkylgroups such as 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, which iscommonly referred to as hexafluoroacetylacetone (HFAA).Hexafluoroacetylacetone provides highly stable volatile coordinationcompounds which are excellent antiknock compounds.

Ligand, L₃, is represented by the formula A-Z-B where A, Z and B are asdefined. The provision in the hydrocarbyl group, Z, of 2 to 3 carbonatoms between A and B is important to provide desired stability byformation of a 5 to 6 membered ring upon chelation of L₃ with the metalion. The hydrocarbyl group, Z, can be in an alkylene group such asethylene, propylene, or alkyl-substituted ethylene or propylene, acycloalkylene or a phenylene group such as 1,2-phenylene.

Representative diamines include ethylenediamine, 1,2-propylenediamine,1,3-propylenediamine, 2-methyl-1,3-diaminepropane,2,2-dimethyl-1,3-diaminopropane, and orthophenylenediamine. Thefollowing methyl substituted diamines, including the correspondingethyl-, propyl- and butyl-substituted diamines, are useful to make thecompounds of this invention: N-methylethylenediamine,N,N-dimethylethylenediamine, N,N'-dimethylethylenediamine,N,N,N'-trimethylethylenediamine, N,N,N',N'-tetramethylethylenediamine,N-methyl-1,2-propylenediamine, N,N-dimethyl-1,2-propylenediamine,N,N'-dimethyl-1,2-propylenediamine,N,N,N'-trimethyl-1,2-propylenediamine,N,N,N',N'-tetramethyl-1,2-propylenediamine,N-methyl-1,3-propylenediamine, N,N-dimethyl-1,3-propylenediamine,N,N-dimethyl-1,3-propylenediamine, N,N,N'-trimethylpropylenediamine,N,N,N',N'-tetramethyl-1,3-propylenediamine,N-methyl-2-methyl-1,3-diaminopropane,N,N-dimethyl-2-methyl-1,3-diaminopropane,N,N'-dimethyl-2-methyl-1,3-diaminopropane,N,N,N'-trimethyl-2-methyl-1,3-diaminopropane,N,N,N',N'-tetramethyl-2-methyl-1,3-diaminopropane,N-methyl-2,2-dimethyl-1,3-diaminopropane,N,N-dimethyl-2,2-dimethyl-1,3-diaminopropane,N,N'-dimethyl-2,2-dimethyl-1,3-diaminopropane,N,N,N'-trimethyl-2,2-dimethyl-1,3-diaminopropane,N,N,N'-tetramethyl-2,2-dimethyl-1,3-diaminopropane,N-methyl-o-phenylenediamine, N,N-dimethyl-o-phenylenediamine,N,N'-dimethyl-o-phenylenediamine, N,N,N'-trimethyl-o-phenylenediamine,N,N,N'-N'-tetramethyl-o-phenylenediamine and the like. The preferreddiamines are N,N,N',N'-tetramethylethylenediamine,N,N,N',N'-tetramethyl-1,2-propylenediamine,N,N,N',N'-tetramethyl-1,3-propylenediamine andN,N,N',N'-tetramethyl-2,2-dimethyl-1,3-diaminopropane. L₃ ligands, otherthan diamines, include aminoethers, aminothioethers, ethers, thioethersand phosphines. Representative compounds include dimethylether ofethylene glycol, dimethylether of propyleneglycol,1-methoxy-2-(dimethylamino)ethane, 1-methylthio-2-(dimethylamino)ethane,1,2-di(ethylthio)ethane, 1,2-di(dimethylphosphino)ethane and the like.

In addition to utility as antiknock additives for fuels, the compoundsof this invention are also useful to introduce the complexed metals intohydrocarbon systems. Because of the intense color of many of thesecompounds, they can be used to color organic systems such as gasoline.They can also be used as combustion control additives for hydrocarbonfuels, such as for control of carbon formation in the combustion of fueloils. They are also useful as octane requirement increase controladditives in internal combustion engines.

Not all of the compounds of this invention exhibit the same degree ofstability, solubility, volatility and antiknock performance. Allcompounds are, however, stable upon exposure to air. They are soluble inhydrocarbon fuels to provide concentrations of metal per gallonsufficient to improve antiknock performance. They are volatile as shownby thermal gravimetric Analysis (TGA) in that at least 20 mg of thecompound is volatilized by the time 250° C. is reached by raising thetemperature 5° C. per minute with nitrogen passed over the sample at 40cc per minute.

The cobalt, nickel and manganese compounds are more stable in fuel thanare the iron compounds. In fact, care must be taken to properlystabilize the iron compounds or they will quickly react with impuritiesin the fuel to lose their antiknock activity and become ineffectual forthat purpose. Alternatively, of course, such iron compounds can beemployed in fuels which are free of the reaction-causing impurities orthey can be used within several hours after introduction into the fuel.

The hydrocarbon fuel to which the compounds are added comprises gasolineor a mixture of hydrocarbons boiling in the gasoline range which isnormally about 32° C. to 220° C. The base fuel can consist ofstraight-chain or branched-chain paraffins, cycloparaffins, olefins andaromatic compounds or any mixture of such hydrocarbons obtainable fromstraight run naphtha, polymer gasoline, natural gasoline, thermally orcatalytically cracked hydrocarbon stocks and catalytically reformedstocks. The gasoline can also contain conventional gasoline additivessuch as antiknock compounds, dyes, antioxidants, anti-icing agents, rustinhibitors, detergents, anti-preignition agents, intake valve depositcontrol additives, antistatic agents, stabilizers and the like.

The compounds of this invention can be added directly to gasoline. Theyalso can be added as concentrates in suitable liquid organic solventssuch as alcohols and hydrocarbons. Particularly suitable solvents arethose hydrocarbons boiling in the gasoline and light hydrocarbon rangesuch as hexane, isooctane, kerosene, toluene and xylene. The concentratecan contain from about 5% to 50%, preferably from about 10% to 40% byweight of the compounds of this invention.

The amount of compound incorporated into gasoline will depend upon theantiknock quality of the base gasoline and the improvement desired. Thecompounds of this invention provide antiknock improvements when used inamounts to provide about 0.01 gram of metal per gallon. Preferably, themetal concentration will be from about 0.02 to 3 grams of metal pergallon, more preferably from about 0.025 to 0.5 gram of metal pergallon.

The following Examples illustrate the invention.

EXAMPLES

The Research Method (ASTM D-909) and the Motor Method (ASTM D-357) wereused to determine the antiknock improving performance of the compoundsof the invention. Generally, the Research Octane Number (RON) isconsidered to be a better guide of antiknock quality when vehicles areoperated under mild conditions associated with low speeds while theMotor Octane Number (MON) is a better indicator when vehicles areoperated at high engine speed or under heavy load conditions. For manyengine operating conditions, some intermediate value between theResearch and the Motor Octane Numbers such as an average, (RON+MON)/₂,is of most interest.

The fuel samples were knock-rated in duplicate and the results arereported as averages of these ratings expressed to the nearest tenth ofan octane number. The gasolines used were representative of commerciallyavailable lead-free gasolines. The specifications of the three gasolinesare given below.

    ______________________________________                                        GASOLINE-SPECIFICATIONS                                                                      Fuel  Fuel      Fuel                                                          A     B         C                                                             °C.                                                                          °C.                                                                              °C.                                     ______________________________________                                        ASTM D-86 Distillation                                                                         33      33        38                                          Initial Boiling Point                                                                         44      44        53                                          5%                                                                           10%              52      52        62                                         20%              67      66        --                                         30%              84      80        97                                         40%              98      93        --                                         50%              109     106       122                                        60%              119     117       --                                         70%              132     129       144                                        80%              146     144       --                                         90%              169     167       179                                        95%              188     183       201                                         Max. Temp.      202     209       219                                         Recovery, Vol. %                                                                              98.0    99.0      98.0                                        Residue, Vol. % 1.0     1.0       1.0                                        ASTM D-287 Gravity 60/60 F                                                                     0.737   0.738     --                                         ASTM D-323 Reid Vapor                                                                          9.9     9.9       7.9                                         Pressure, lb                                                                 ASTM D-525 Induction Period                                                                    No      No        No                                                          Break   Break     Break                                      ASTM D-3120 Sulfur, wt %                                                                       0.014   0.038     0.034                                      ASTM D-1319 Hydrocarbon                                                        Types                                                                         Saturates, Vol. %                                                                             73      68        61                                          Olefins, Vol. % 3       8         8                                           Aromatics, Vol. %                                                                             24      24        31                                         ASTM D-909 Research Octance                                                                    91.4    89.3      91.4                                        No.                                                                          ASTM-D D-357 Motor Octane                                                                      81.8    83.8      82.0                                        No.                                                                            (R + M)/.sub.2 Octane No.                                                                    86.6    86.6      86.7                                       ______________________________________                                    

EXAMPLE 1Bis(hexafluoroacetylacetonato)cobalt(II)tetramethylethylenediamine,Co(II) (HFAA)₂.TMED

To a 2-liter reaction flask equipped with a mechanical stirrer, acondenser, a gas inlet tube and an addition funnel, 700 ml of deionizedwater was added. The water was sparged for 1/2 hour with nitrogen atreflux and then cooled to room temperature. Hexafluoroacetylacetone(HFAA), CF₃ --C(O)--CH₂ --C(O)--CF₃, was then added in an amount of 104g over a period of 15 minutes. A temperature rise of 5° C. was noted.After stirring for 15 minutes, 20.4 g of sodium hydroxide dissolved in70 ml of water was added over 17 minutes. Cobaltous chloride solution(59.5 g of CoCl₂.6H₂ O dissolved in 280 ml of water) was added over 15minutes. Yellow precipitate formed initially and gradually turned lightgreen. After stirring for 1 hour, 29 g of tetramethylethylenediamine(TMED), (CH₃)₂ NCH₂ CH₂ N(CH₃)₂, was added. The color of the precipitatechanged from light green to brownish-yellow. After stirring for anadditional 21/2 hours, the reaction mass was filtered and the solidswashed with water. The filter cake (89.6 g) was heated with 450 ml. oftoluene and filtered. Removal of the solvent from the filtrate provided78 g (53% yield) of rust-colored product which melted at 100° to 101.5°C. A portion of the product was recrystallized from petroleum ether.Elemental analysis: Calculated for Co(C₁₆ H₁₈ N₂ O₄ F₁₂): C, 32.6; H,3.1; N, 4.8; F, 38.7; Co, 10.0. Found: C, 32.5; H, 2.9; N, 4.7; F, 38.2;Co, 10.2.

Thermogravimetric analyses of Co(II) (HFAA)₂.TMED were carried out in aDu Pont 990 Thermal Analyzer coupled to a Du Pont 951 ThermogravimetricAnalyzer. In these characterizations a sample (about 20 mg) was heatedover a temperature range of 25° to 500° C. at a heating rate increase of5° C. per minute with nitrogen or air as the carrier gas at a gas flowrate of 40 ml per minute. The loss in sample weight was recordedcontinuously.

The thermogravimetric analysis carried out with nitrogen as the carriergas provided information on the volatility and thermal stability of thecompound. The analysis carried out with air as the carrier gas, inaddition to volatility and thermal stability information providedinformation on the oxidation stability of the compound; thermal oroxidative instability being indicated by discontinuous weight loss andincomplete volatilization of the metal residues. The following datademonstrate the good volatility, and thermal and oxidative stability ofCo(II) (HFAA)₂.TMED.

    ______________________________________                                        THERMOGRAVIMETRIC ANALYSIS                                                    Co(II) (HFAA).sub.2.TMED                                                      Carrier Gas = Nitrogen                                                                         Carrier Gas = Air                                            Sample Wt. 18.3 mg                                                                             Sample Wt. 23.4                                                      Wt. % Vola-              Wt. % Vola-                                  Temp. °C.                                                                      tilized      Temp. °C.                                                                          tilized                                      ______________________________________                                         75     0.0           75         0.0                                           90     0.3           90         0.4                                          100     1.1          100         0.8                                          110     2.7          110         1.2                                          120     6.0          125         3.8                                          125     7.6          150         16.2                                         135     12.6         160         25.2                                         140     15.3         170         42.3                                         150     22.4         175         50.8                                         160     34.4         185         78.6                                         170     51.9         190         91.5                                         175     61.7         200         100.0                                        185     89.1                                                                  187     100.0                                                                 ______________________________________                                    

EXAMPLE 2Bis(Pivaloyltrifluoroacetonato)cobalt(II)tetramethylethylenediamine,Co(II) (PTFA)₂.TMED

To a 2-liter reaction flask equipped with a mechanical stirrer, acondenser, a gas inlet tube and an addition funnel, 560 ml of denaturedethyl alcohol was added. The alcohol was heated to reflux and spargedwith nitrogen and allowed to cool. Pivaloyltrifluoroacetone (PTFA),(CH₃)₃ C--C(O)--CH₂ --C(O)--CF₃, was then added in an amount of 78.5grams over 10 minutes. Sodium hydroxide solution (16.3 g of sodiumhydroxide dissolved in 56 ml water) was then added over a period of 19minutes. A temperature rise of 5° C. was noted. After stirring for 15minutes, cobaltous chloride solution (47.6 g CoCl₂.6H₂ O dissolved in224 ml of water) was added over 17 minutes. Dark red precipitate formed.The reaction mixture was stirred for 1 hour and 23.2 g oftetramethylethylenediamine (TMED), (CH₃)₂ NCH₂ CH₂ N(CH₃)₂, was addedover 15 minutes causing the temperature to rise 2.5° C. After stirringfor an additional 21/2 hours, the reaction mass was filtered and theprecipitate washed with water. The product was extracted into 35 ml oftoluene by stirring, then filtered. Removal of toluene provided 81.5 gof red, sticky solid. Recrystallization from petroleum ether provided 39g of orange solid. The orange solid appeared to melt at 157° C. (nosolid remaining but no liquefaction) and was completely liquid at 196°C. Elemental analysis: Calculated for Co(C₂₂ H₃₆ O₄ N₂ F₆): C, 46.7; H,6.4; N, 5.0; F, 20.2; Co, 10.4. Found: C, 47.4; H, 6.0; N, 5.1; F, 19.8;Co, 10.8.

Thermogravimetric analyses of Co(II) (PTFA)₂.TMED were carried out aspreviously described and the results, summarized below, demonstrate itsgood volatility and oxidative and thermal stability.

    ______________________________________                                        THERMOGRAVIMETRIC ANALYSIS                                                    Co(II) (PTFA).sub.2 . TMED                                                    Carrier Gas = Nitrogen                                                                         Carrier Gas = Air                                            Sample Wt. 17.2 mg                                                                             Sample Wt. 19.9 mg                                                   Wt. % Vola-              Wt. % Vola-                                  Temp. °C.                                                                      tilized      Temp. °C.                                                                          tilized                                      ______________________________________                                         75     0.0           75         0.0                                          100     1.2          100         0.5                                          125     1.7          125         1.0                                          150     3.5          150         2.5                                          175     11.0         175         9.5                                          200     33.7         200         29.6                                         210     51.2         210         47.8                                         220     76.7         220         72.7                                         225     93.0         225         87.4                                         233     100.0        233         100.0                                        ______________________________________                                    

EXAMPLE 3Bis(trifluoroacetylacetonato)cobalt(II)tetramethylethylenediamine,Co(II) (TFAA)₂.TMED

To a 3-liter reaction flask equipped with a mechanical stirrer, acondenser, a gas inlet tube and an addition funnel, 1120 ml of deionizedwater was added. The water was heated to reflux and sparged withnitrogen and cooled. Trifluoroacetylacetone (TFAA), CF₃ --C(O)--CH₂--C(O)--CH₃, 123.3 g, was added and after stirring for 15 minutes, asolution of sodium hydroxide (32.7 g of sodium hydroxide dissolved in112 ml of water) was added over a period of 20 minutes. A temperaturerise of 4° C. was noted. Cobaltous chloride solution (95.2 g ofCoCl₂.6H₂ O dissolved in 448 ml water) was added over 25 minutes causinga formation of light brown precipitate. After stirring for 1 hour,tetramethylethylenediamine (TMED), (CH₃)₂ N--CH₂ --CH₂ --N(CH₃)₂ wasadded. The color of the precipitate changed to green. The reactionmixture was stirred for 21/2 hours and filtered. The precipitate waswashed with water and dried on a porous plate. The product was extractedinto 900 ml of toluene by stirring at room temperature, then filtered.Evaporation of toluene from the filtrate provided 58.6 g (30% yield) ofthe product. The product was recrystallized from petroleum either toprovide a reddish orange solid, m.p. 85.5° C. Elemental analysis:Calculated for Co(C₁₆ H₂₄ N₂ O₄ F₆): C, 39.9; H, 5.0; N, 5.2; F, 23.7;Co, 12.2. Found: C, 40.2; H, 4.9; N, 5.8; F, 22.4; Co, 12.3.

Thermogravimetric analyses of Co(II) (TFAA)₂.TMED were carried out aspreviously described and the results, summarized below, demonstrate goodvolatility and oxidative and thermal stability.

    ______________________________________                                        THERMOGRAVIMETRIC ANALYSIS                                                    Co(II) (TFAA).sub.2 . TMED                                                    Carrier Gas = Nitrogen                                                                         Carrier Gas = Air                                            Sample Wt. 20.1 mg                                                                             Sample Wt. 26.2 mg                                                   Wt. % Vola-              Wt. % Vola-                                  Temp. °C.                                                                      tilized      Temp. °C.                                                                          tilized                                      ______________________________________                                         75     0.0           75         0.0                                           90     0.2          100         0.0                                          100     0.5          125         2.2                                          110     1.0          150         8.0                                          125     3.0          160         12.2                                         135     5.5          170         18.0                                         150     13.0         175         22.2                                         165     24.0         180         27.5                                         175     36.3         190         40.9                                         190     61.4         200         61.8                                         200     83.8         210         86.7                                         205     95.0         218         100.0                                        208     100.0                                                                 ______________________________________                                    

EXAMPLES 4 to 19

The following compounds were prepared by sequential addition of aperfluoroalkyl-containing β-diketone and a diamine ligand to the metalsalts in the presence of a base. Each of the compounds is stable in airand is soluble in hydrocarbons. Thermogravimetric analysis (TGA) dataindicate that each of the compounds is substantially completelyvolatilized by about 250° C. Each of the compounds is stable inhydrocarbon solutions indefinitely. With the iron compounds (Examples14,15 and 16), the solutions in a hydrocarbon solvent or other organicsolvent are stable provided the solvents are free of peroxides. In thepresence of the peroxides, the iron compounds appear to undergo somereaction to precipitate iron compounds of unknown composition.

In the Table, these abbreviations are used:PTFA=pivaloyltrifluoroacetone; HFAA=hexafluoroacetylacetone;TFAA=trifluoroacetylacetone;TMPD=N,N,N',N'-tetramethyl-1,3-propylenediamine;HMPD=N,N,N',N'-2,2-hexamethylpropylenediamine;TMED=N,N,N',N'-tetramethylenediamine; ED=ethylenediamine; andTGA=Thermogravimetric Analysis. The temperatures are those recorded fromthe start of volatilization until the end of the test.

    ______________________________________                                                             TGA                                                                                                 % Vol-                                         Diketone Diamine               atil-                              Ex.  M.sup.2+                                                                             Ligand   Ligand m.p. °C.                                                                      Temp. °C.                                                                      ized                               ______________________________________                                         4   Co     HFAA     TMPD   128-129                                                                              110-187 100                                 5   Co     HFAA     HMPD   96.0-97.5                                                                            110-190 100                                 6   Mn     HFAA     TMED   83.0-84.0                                                                            110-175  99                                 7   Mn     PTFA     TMED   --     --      --                                  8   Mn     TFAA     TMED   96.5-97.5                                                                            --      --                                  9   Mn     HFAA     TMPD   95.0-96.0                                                                            100-250 100                                10   Mn     HFAA     ED     --     --      --                                 11   Mn     TFAA     ED     --     --      --                                 12   Mn     HFAA     HMPD   86.0-87.5                                                                            115-225  91                                13   Mn     PTFA     ED     --     --      --                                 14   Fe     TFAA     TMED   98-99  115-210  95                                15   Fe     HFAA     TMED   32-83  125-192 100                                16   FE     HFAA     HMPD   87-89  --      --                                 17   Ni     TFAA     TMED   78.0-78.5                                                                            105-210 100                                18   Ni     HFAA     TMED   128-130                                                                              125-186 100                                19   Ni     HFAA     HMPD   116-117                                                                              --      --                                 ______________________________________                                    

EXAMPLE 20(Acetylacetonatohexafluoroacetylacetonato)cobalt(II)tetramethylethylenediamine,Co(II) (AA) (HFAA).TMED

This Example concerns compounds of the invention wherein one β-diketonecontains perfluoroalkyl substituents and the other β-diketone does not.

Into a 1-liter reaction flask equipped with an agitator, a condensor, athermometer, an addition funnel and a gas inlet tube, were placedcobaltous acetate (12.4 g, 0.05 mole) and 200 ml of water. The mixturewas purged with nitrogen gas for 15 minutes then cooled to 5° C. and asolution of 2,4-pentanedione (acetylacetone, AA) (5.0 g, 0.05 mole) in25 ml of absolute ethanol was added dropwise. After stirring for 15minutes, 2.6 g (0.025 mole) of sodium carbonate was added. The reactionmixture was allowed to warm to room temperature andhexafluoroacetylacetone (HFAA) (10.4 g, 0.05 mole) dissolved in 25 ml ofabsolute ethanol was added dropwise. The reaction mixture was orange incolor. Sodium carbonate (2.6 g, 0.025 mole) was then added followed byN,N,N',N'-tetramethylethylenediamine (TMED) (11.6 g; 0.10 mole)dissolved in 200 ml of benzene. The reaction mixture was stirred for 1hour. The benzene phase was separated and washed with 50 ml of water.Removal of benzene provided 22.5 g (93.5% yield) of red compound whichmelted at 49°-50° C. A one-gram sample was sublimed (50° C. and 0.2 minpressure) to provide a brick-red solid, m.p. 50°-51° C. Elementalanalyses: Calculated for CoC₁₆ H₂₄ O₄ F₆ H₂ %: C, 39.9; H, 5.0; N, 5.8;F, 23.7; Found: C, 39.2; H, 5.0; N, 5.8; F, 23.2. Thermogravimetricanalysis indicated smooth volatilization with 5% volatilization at 123°C. and 100% volatilization at 200° C.

High Resolution Mass Spectrometry (HRMS) of a sample introduced directlyinto the ionization chambers at 50° C. showed an intense peakcorresponding to 481.0970 mass number which corresponded to themolecular weight of 481.303 for the compound with mixed β-diketoneligands. On the basis of its sharp melting point (50°-51° C., unchangedon sublimation), elemental analysis, smooth TGA curve and massspectrometric analysis, the compound was identified as Co(II) (AA)(HFAA).TMED and not a physical mixture of Co(II) (AA)₂.TMED, Co(II)(HFAA)₂.TMED, and Co(II) (AA) (HFAA).TMED.

When the sample made by the procedure of this Example was preheated to200° C. before ionization in the mass spectrometer, intense fragmentsfrom Co(II) (AA)₂.TMED and Co(II)(HFAA)₂.TMED were found thus indicatingthat compounds with mixed β-diketone ligands undergo ligand exchange at200° C.

EXAMPLE 21(Isovalerylacetonetrifluoroacetylacetone)cobalt(II)tetramethylethylenediamine,Co(II) (IVA) (TFAA).TMED

By the procedure substantially as described above except for thesubstitution of 2-methyl-4,6-heptanedione (isovalerylacetone, IVA) foracetylacetone and of trifluoroacetylacetone (TFAA) forhexafluoroacetylacetone, Co(II) (IVA) (TFAA).TMED was prepared.Elemental analysis: Calculated for CoC₁₉ H₃₃ O₄ N₂ F₃ : C, 48.6; H, 7.1;N, 6.0 and F, 12.1. Found: C, 46.9; H, 6.8; N, 5.9 and F, 12.2. Thecompound is a red-brown liquid which is very volatile (93%volatilization between 100° C. to 130° C.).

EXAMPLES 22 to 31

Antiknock performances of the compounds of this invention weredetermined by the Research and the Motor Methods as described. The ironcompound of Example 25 was tested for antiknock activity before itreacted with fuel impurities, i.e., it was tested within several hoursof its introduction into the fuel. The results obtained with the threepreviously described gasolines are summarized below.

    ______________________________________                                        ANTIKNOCK PERFORMANCE                                                                           Increase in Octane                                                            Number (ΔON)                                                                  Re-     Mo-                                           Ex. No.                                                                              Metal/           search  tor                                           Fuel   Gallon (G)       (R)     (M)  (B + M)/2                                ______________________________________                                        22/    Co(II) (HFAA).sub.2 TMED                                               Fuel A                                                                                0.025           1.7     0.6  1.1                                             0.05             2.6     1.1  1.8 j - 0.10 3.0 1.2 2.1                        0.15             3.6     1.5  2.5                                             0.20             4.2     1.9  3.2                                             0.25             4.5     1.9  3.2                                      23/    Co(II)(TFAA).sub.2.TMED                                                Fuel A                                                                                0.025           1.5     0.1  0.8                                             0.05             2.1     0.6  1.3                                             0.10             2.7     1.0  1.8                                             0.15             3.2     1.4  2.3                                             0.20             3.6     1.8  2.7                                             0.25             4.0     2.0  3.0                                      24/    Co(II) (PTFA).sub.2.TMED                                               Fuel A                                                                                0.025           1.2     0.3  0.7                                             0.05             0.2     0.3  0.2                                             0.10             -0.3    0.6  0.1                                             0.15             1.9     0.7  1.3                                             0.20             3.2     1.8  2.5                                             0.25             3.5     1.7  2.6                                      25/    Fe(II) (TFAA).sub.2.TMED                                               Fuel B                                                                                0.025           0.0     0.5  0.3                                             0.05             0.3     0.3  0.3                                             0.10             -0.5    0.1  -0.2                                            0.20             0.9     0.2  0.6                                      26/    Ni(II) (TFAA).sub.2.TMED                                               Fuel B                                                                                 0.025          0.6     0.0  0.3                                             0.05             1.1     0.3  0.7                                             0.10             1.9     0.6  1.3                                             0.20             2.6     0.9  1.8                                      27/    Co(II) (AA) (HFAA).TMED                                                Fuel B                                                                                0.025           1.1     0.5  0.8                                             0.05             1.5     0.8  1.2                                             0.10             2.3     1.1  1.7                                             0.15             2.9     1.3  2.1                                             0.20             3.3     1.5  2.4                                             0.25             4.1     1.8  2.9                                      28/    Mn(II) (HFAA).sub.2.TMED                                               Fuel C                                                                                0.025           0.5     0.3  0.4                                             0.05             1.0     0.5  0.8                                             0.10             1.5     1.0  1.3                                             0.15             1.8     1.2  1.5                                             0.20             2.0     1.1  1.5                                             0.25             2.1     1.6  1.9                                             0.30             2.2     1.8  2.0                                      29/    Mn(II) (PTFA).sub.2.TMED                                               Fuel C                                                                                0.025           0.3     0.1  0.2                                             0.05             0.6     0.4  0.5                                             0.10             0.7     0.5  0.6                                             0.15             1.2     0.6  0.9                                             0.20             1.3     0.7  1.0                                             0.25             1.4     0.8  1.1                                             0.30             1.4     0.7  1.2                                      30/    Mn(II) (TFAA).sub.2.TMED                                               Fuel C                                                                                0.025           0.3     0.1  0.2                                             0.05             0.7     0.2  0.5                                             0.10             1.0     0.5  0.8                                             0.15             1.0     0.6  0.8                                             0.20             0.9     0.7  0.8                                             0.25             1.0     0.5  0.8                                             0.30             1.1     0.7  0.9                                      31/    Co(II) (HFAA).sub.2.TMED                                               Fuel C                                                                                0.025           1.7     0.9  1.3                                             0.05             2.2     1.4  1.8                                             0.10             2.8     1.9  2.4                                             0.15             3.3     2.1  2.7                                             0.20             3.7     2.4  3.1                                             0.25             4.1     2.6  3.3                                             0.30             4.1     2.6  3.3                                      ______________________________________                                    

The above results show that each of the compounds of this inventionprovides improvements in the octane numbers in each of the threegasolines. The improvements provided by the cobalt and the nickelcompounds are outstanding.

EXAMPLE 32 INCLUDING COMPARISONS

The compound of Example 1, Co(II) (HFAA)₂.TMED, was compared inantiknock efficiency with two commercial metal-containing antiknockcompounds: tetraethyllead, andmethylcyclopentadienylmanganesetricarbonyl, also known as "MMT". Thecomparison was made in a commercial lead-free gasoline (Fuel C) whosespecifications were provided earlier. The knock ratings were carried outby ASTM D-909 (Research) and ASTM D-357, (Motor Methods) in duplicates,and the results are expressed in terms of octane number increase (ΔON)to the nearest tenth (0.1) of the octane numbers. The results are alsoexpressed in terms of (R+M)/2, which values show good correlation withroad octane improvements.

    ______________________________________                                        ANTIKNOCK PERFORMANCE (Comparison)                                            Gms of      Octane Number Increase (ΔON)                                Metal per   Research   Motor                                                  Gallon      (R)        (M)       (R + M)/2                                    ______________________________________                                        Antiknock Additive = Tetraethyllead (as Motor Mix)                             0.025      0.3        0.2       0.3                                          0.05        0.3        0.2       0.3                                          0.10        0.8        0.5       0.7                                          0.15        1.0        0.6       0.8                                          0.20        1.5        1.0       1.3                                          0.25        1.7        1.5       1.6                                          0.30        1.9        1.6       1.8                                          ______________________________________                                        Antiknock Additive = methylcyclopentadienyl-                                  manganesetricarbonyl (Comparison)                                              0.025      0.7        0.6       0.7                                          0.05        1.1        0.6       0.9                                          0.10        1.9        1.1       1.5                                          0.15        2.4        1.2       1.8                                          0.20        2.6        1.3       2.0                                          0.25        3.0        1.6       2.3                                          0.30        3.1        1.8       2.5                                          ______________________________________                                        ANTIKNOCK PERFORMANCE (Example 32)                                            Gms of      Octane Number Increase (ΔON)                                Metal per   Research   Motor                                                  Gallon      (R)        (M)       (R + M)/2                                    ______________________________________                                        Antiknock Additive = Co(II) (HFAA).sub.2.TMED                                 (Invention Compound)                                                           0.025      1.7        0.9       1.3                                          0.05        2.2        1.4       1.8                                          0.10        2.8        1.9       2.4                                          0.15        3.3        2.1       2.7                                          0.20        3.7        2.4       3.1                                          0.25        4.1        2.6       3.3                                          0.30        4.1        2.6       3.4                                          ______________________________________                                    

The above results demonstrate the outstanding and unexpected antiknockefficiency of the invention compound.

The Research Octane Number data show that 0.025 g per gallon of cobaltas Co(II) (HFAA)₂.TMED provides an increase of 1.7 octane number whereasthe same concentration of manganese as MMT provides an increase of 0.7octane number and of lead as tetraethyllead provides an increase of 0.3octane number. Expressed in another way: at 0.025 g per gallon treatinglevel, cobalt in the compounds of this invention has an efficiency whichis 243% greater than manganese and 563% greater than lead.

The following Table summarizes the superiority of the cobalt compoundsof this invention in improving the Research Octane Numbers over the twocommercially used antiknock compounds. Similar comparisons can be madefor Motor and (R+M)/2 Octane increases.

    ______________________________________                                        Comparative Research Octane Number Increase                                   Gms of                                                                        Metal per      Percent Efficiency of Cobalt .sup.1 Over                       Gallon         Manganese.sup.2                                                                              Lead.sup.3                                      ______________________________________                                         0.025         243            563                                             0.05           200            732                                             0.10           147            350                                             0.15           138            280                                             0.20           142            247                                             0.25           137            241                                             0.30           132            216                                             ______________________________________                                         .sup.1 Cobalt as Co(II) (HFAA).sub.2.TMED                                     .sup.2 Manganese as methylcyclopentadienylmanganesetricarbonyl                .sup.3 Lead as tetraethyllead                                            

The above Table shows the superiority of cobalt over manganese and lead.It also shows that the degree of superiority increases with decreasingconcentration of the metals. Enhanced superiority at low metalconcentration is important since the desired octane number increase canbe achieved with a lesser amount of cobalt than either manganese or leadwith attendant decrease in difficulties generally believed to beassociated with use of metal-containing additives in gasoline.

EXAMPLE 33

The compound of Example 1, Co(II) (HFAA)₂.TMED, was tested as anantiknock additive in a Road Octane Test carried out according to theModified Uniontown Method (CRC F-28-70). These tests used a fleet ofnine automobiles identified as follows:

    ______________________________________                                                                         Brake                                                   No.    Comp.   Displ. Horse- Carb.                                 Automobile*                                                                              Cyl.   Ratio   cu in  power  bbl.                                  ______________________________________                                        Oldsmobile 8      8.0     350    170    4                                     Cutlass                                                                       Chevrolet  8      8.5     305    145    2                                     Impala                                                                        Ford LTD   8      8.0     351 M  161    2                                     Ford Granada                                                                             8      8.0     302    129    2                                     Pontiac    8      7.6     400    180    4                                     Catalina                                                                      Plymouth Fury                                                                            8      8.5     318    145    2                                     Chevrolet Nova                                                                           6      8.3     250    110    1                                     Chevrolet Nova                                                                           6      8.3     250    110    1                                     Ford Pinto 4      9.0     140     83    2                                     ______________________________________                                         *All had automatic transmissions except for one of the 1977 Chevrolet         Novas. All were 1977 models except the Ford Granada which was a 1976          model.                                                                   

The gasoline used was Fuel B whose specifications were given earlier.The ratings were carried out in triplicate and the average octane numberincrease (ΔON) for the 9 cars is summarized below in terms of increasein octane numbers (ΔON) over the octane number of the base fuel. Forcomparison, the tests were also carried out using commercial manganeseantiknock compound, methylcyclopentadienylmanganesetricarbonyl ("MMT").The results demonstrate that the cobalt compounds provide outstandingantiknock performance under actual use conditions.

    ______________________________________                                        ROAD ANTIKNOCK PERFORMANCE                                                    Nine-Car Average                                                              Modified Uniontown Ratings in Triplicate                                      Base Fuel Road Octane Rating = 89l.3                                          Gms of                                                                        metal per  Road Octane Number Increase (ΔON)                            gallon     "MMT"       Co(II) (HFAA).sub.2 TMED                               ______________________________________                                        0.025      0.48        0.84                                                   0.050      not         1.45                                                              determined                                                         0.10       1.40        1.99                                                   0.20       not                                                                           determined  2.61                                                   ______________________________________                                    

EXAMPLES 34 TO 37

Antiknock performances of Ni(II) (HFAA)₂.TMED (Example 18), Ni(II)(HFAA)₂.HMPD (Example 19), Fe(II) (HFAA)₂.TMED (Example 15) and Fe(II)(HFAA)₂.HMPD (Example 16) were determined in Fuel B by the ResearchMethod. The iron compounds of Examples 36 and 37 were tested forantiknock activity before they reacted with fuel impurities, i.e., theywere tested within several hours of their introduction into the fuel.The results, summarized below, show that each of the compounds provideimprovements in the octane rating of the fuel.

    ______________________________________                                        ANTIKNOCK PERFORMANCES                                                        Grams of Metal/Gallon                                                         Compound                                                                      Research Octane Number Increase (ΔON)                                   Ex.  0.025   0.05   0.10          0.15 0.20 0.25                              ______________________________________                                                            Ni(II) (HFAA).sub.2.TMED                                                                    S                                           34   0.7     1.4    2.7           3.3  3.8  4.4                                                   Ni(II) (HFAA).sub.2.HMPD                                  35   0.4     0.9    1.8           2.3  3.0  3.5                                                   Fe(II) (HFAA).sub.2.TMED                                  36   -0.7    0.9    1.1           1.4  1.6  2.1                                                   Fe(II) (HFAA).sub.2.HMPD                                  37   0.4     0.6    0.9           0.8  1.1  --                                ______________________________________                                    

EXAMPLE 38 Preparation of Bis(difluoroacetylacetonyl)Cobalt(II).TMED

In a dry 250 ml reaction flask equipped with a stirrer, a condenser, gasinlet tube, an addition funnel, and a connection to a wet test meter tomeasure hydrogen evolution, were placed 60 ml of diethylether and 14.4 gof sodium hydride (50% in oil). The addition funnel was charged with asolution consisting of 29.7 g of difluoromethyl acetate, 17.4 g of dryacetone and 40 ml of dry diethylether. The reaction flask was cooled to0° C. and the solution in the addition flask was added over a two-hourperiod. During the addition of difluoromethylacetate, evolution of 7.7liters of hydrogen was noted. The reaction mixture was allowed to warmto room temperature and was stirred overnight under nitrogen atmosphere.A solution of 18 g of acetic acid in 120 ml of water was then added. Thereaction mass changed from a light gray slurry to a two-phase liquidsystem consisting of an almost white ether layer and a dark brown clearaqueous layer. The aqueous layer was transferred to a 1 liter reactionflask and 33.6 gms of cobaltous acetate dissolved in 300 ml of water wasadded over a 30 minute period. The reaction mass was stirred for 30minutes and 6.3 g of sodium carbonate was added, and the stirring wascontinued for an additional 30 minutes. The reaction mixture wasfiltered, and the precipitate was allowed to dry overnight. A 36.6 g(82%) yield of bis(difluoroacetylacetonyl)cobalt was obtained.

Bis(difluoroacetylacetonyl)cobalt, 34.7 g, was slurried in 500 ml ofbenzene in a 1 liter reaction flask equipped with a stirrer, acondenser, gas inlet tube, and an addition funnel.Tetramethylethylenediamine, 12.8 g, was then added over a 15 minuteperiod. The reaction mass was heated to reflux for 4 hours during whichtime 4.2 ml of water was removed. The reaction mixture was cooled andfiltered. Toluene was removed from the filtrate at 65° C. and 26 to 30mm pressure providing 39.2 g (88% theory) of deep red oil which uponstanding crystallized into brittle red solid. A 1 g sample wasrecrystallized in 3 ml of petroleum ether, providing 0.5 g of pinkcrystal which melted in the range of 83.5° to 84.5° C. Elementalanalysis indicated that the compound contained 44.9% C, 6.0% H and 6.0%N; the theoretical values being 43.1% C, 5.8% H and 6.3% N.

EXAMPLE 39 Preparation ofBis(chlorodifluoroacetylacetonyl)Cobalt(II).TMED

In a dry 250 ml reaction flask equipped with a stirrer, a condenser, gasinlet tube, an addition funnel, and a connection to a wet test meter tomeasure hydrogen evolution, were placed 40 ml of diethylether and 9.6 gof sodium hydride (50% in oil). The addition funnel was charged with asolution consisting of 28.5 g of ethylchlorodifluoroacetate, 11.6 g ofdry acetone and 25 ml of diethylether. The reaction flask was cooled to0° C. and the solution in the addition funnel was added over athree-hour period keeping the reaction temperature at 0° C.±2°. A totalof 5.05 liters of hydrogen was evolved. After standing overnight at roomtemperature, 12 g of glacial acetic acid in 50 ml of water was added.The reaction mass turned from a gray slurry to a dark brown two-phasesystem. The reaction mass was transferred to a 500 ml reaction flask anda solution of 22.4 g of cobaltous acetate in 200 ml of water was added,dropwise. After stirring for 30 minutes, 4.2 g of sodium carbonate wasadded in portions. The reaction mass was filtered to yield 27.8 g (77%theory) of crude bis(chlorodifluoroacetylacetonyl)Co(II). A portion ofthe crude which was recrystallized from a toluene-petroleum ethermixture melted in the range of 181° to 183° C. Elemental analysisindicated that the chelate was a monohydrate: % C, 29.0; % H, 2.3; % Co,14.1; with the theoretical values for the monohydrate being: % C, 28.8;% H, 2.4; and % Co, 14.2.

In a 1 liter reaction flask equipped with a thermometer, a condenser andan addition funnel, were placed 24.3 g of the above describedbis(chlorodifluoroacetylacetonyl)Co(II) monohydrate and 500 ml oftoluene. Tetramethylethylenediamine, 7.8 g, was added from the additionfunnel over a ten-minute period. The reaction mixture was heated toreflux and kept on reflux until no more water separated. A total of 3 mlof water was collected. The reaction mixture was then filtered and thetoluene removed at 60° to 70° C. under reduced pressure to provide 25.5g of viscous ruby-red oil. Upon standing for a few days, most of the oilcrystallized. Recrystallization from petroleum ether provided 15 g ofmaterial melting in the range of 71° to 72.5° C. Elemental analysisshowed: % C, 38.9; % H, 4.7; % N, 5.5; and % Co, 11.5; with thetheoretical values for bis(chlorodifluoroacetonyl)Co(II).TMED being: %C, 37.4; % H, 4.7; % N, 5.5; and % Co, 11.5.

EXAMPLES 40 TO 45

The following Examples concern compounds of the invention whereindifferent combinations of ligands L₁, L₂ and L₃ are used with cobalt asthe metal. The preparation of these compounds was accomplished bycombining cobalt (M⁺⁺) ions with the β-diketone ligands followed bycombination thereof with ligand, L₃.

The compounds are described in the following Table wherein HFAA standsfor hexafluoroacetylacetone and ligand, L₃, is described in terms ofA-Z-B, and TGA is thermogravimetric analysis.

    __________________________________________________________________________                                  TGA                                                                                   Vola-                                                 L.sub.3         m.p.                                                                              Temp.                                                                             til-                                    Ex.                                                                              L.sub.1 and L.sub.2                                                                      A    Z     B    °C.                                                                        °C.                                                                        ized                                    __________________________________________________________________________    40 HFAA       CH.sub.3 O                                                                         CH.sub.2 CH.sub.2                                                                   OCH.sub.3                                                                          57-58                                                                              50-185                                                                           90                                      41 HFAA       CH.sub.3 O                                                                         CH.sub.2 CH.sub.2                                                                   N(CH.sub.3).sub.2                                                                  72-73                                           42 HFAA       CH.sub.3 S                                                                         CH.sub.2 CH.sub.2                                                                   N(CH.sub.3).sub.2                                                                  87-88                                                                             105-203                                                                           100                                     43 HFAA       C.sub.2 H.sub.5 S                                                                  CH.sub.2 CH.sub.2                                                                   SC.sub.2 H.sub.5                                                                   57-59                                                                             120-207                                                                           90                                      44                                                                                ##STR4##  (CH.sub.3).sub.2 N                                                                 CH.sub.2 CH.sub.2                                                                   N(CH.sub.3).sub.2                                                                  138-139                                                                           293 90                                      45 HFAA       NH.sub.2                                                                            ##STR5##                                                                           NH.sub.2                                                                           111-112                                                                           215 90                                      __________________________________________________________________________

The compounds of Examples 38 to 43 give good octane ratings improvementin fuel as shown in the following Table wherein the fuel is Fuel A whosespecifications appear, supra, preceding Example 1.

    ______________________________________                                        Antiknock Performance Of Representative                                       Compounds in Fuel A                                                                             Increase in Octane                                          Com-              Number (ΔON)                                          pound  Gms of     Re-                                                         of     metal per  search    Motor   R + M)/                                   (Ex. No.)                                                                            gallon     (R)       (M)     2                                         ______________________________________                                        38      0.025     0.7       0l4     0.6                                              0.05       1.3       0.7     1.0                                              0.10       1.8       1.1     1.5                                              0.20       2.7       1.5     2.1                                              0.30       3.5       1.6     2.6                                       39      0.025     0.8       0.3     0.6                                              0.05       1.2       0.6     0.9                                              0.10       1.5       0.8     1.1                                              0.20       2.4       1.4     1.9                                              0.30       2.5       1.6     2.1                                       40      0.025     0.6       0.4     0.5                                              0.05       0.8       0.7     0.8                                              0.10       1.6       0.9     1.3                                              0.15       2.0       1.1     1.6                                              0.20       2.5       1.3     1.9                                              0.30       3.2       1.8     2.5                                       41      0.025     1.1       0.5     0.8                                              0.05       1.9       0.8     1.4                                              0.10       2.6       1.5     2.1                                              0.15       3.2       1.8     2.5                                              0.20       3.6       2.0     2.8                                              0.30       4.4       2.3     3.4                                       42      0.025     1.0       0.2     0.6                                              0.5        1.7       0.5     1.1                                              0.10       2.4       0.9     1.7                                              0.15       2.9       1.2     2.1                                              0.20       3.1       1.3     2.2                                              0.30       4.1       1.6     2.9                                       43      0.025     0.6       0.3     0.5                                              0.05       0.9       0.6     0.8                                              0.10       1.6       0.6     1.1                                              0.15       1.6       1.2     1.4                                              0.20       1.9       1.1     1.5                                       ______________________________________                                    

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A compound having thestructure ##STR6## wherein M is a divalent metal selected from the groupMn, Fe, Co and Ni,L₁ and L₂ are the same or different chelate-formingβ-diketone groups having from 5 to 20 carbon atoms, one or both of L₁and L₂ having at least one polyfluoroalkyl group, --CF₂ X, adjacent tothe carbonyl group, X is selected from the group H, F, Cl, phenyl, C₁-C₆ alkyl and C_(n) F_(2n) Y, n is 1 to 6, Y is H, F, or Cl, L₃ is aligand having the structure, A-Z-B,wherein A and B are the same ordifferent members of the group --NH₂, --NHR₅, --NR₅ R₆, OH, OR₅, SH, SR₅and PR₅ R₆, R₅ and R₆ are the same or different members of the group C₁to C₄ alkyl, and Z is a divalent hydrocarbyl group having 2 to 10 carbonatoms selected from a member of the group alkylene, phenylene andcycloalkylene, each member providing 2 or 3 carbon atoms between A andB, with the proviso that when Z is phenylene, the number of carbon atomsbetween A and B is
 2. 2. A compound according to claim 1 wherein each ofL₁ and L₂ is the difluoroacetylacetonyl β-diketone group.
 3. A compoundaccording to claim 1 wherein each of L₁ and L₂ is thechlorodifluoroacetylacetonyl β-diketone group.
 4. A compound accordingto claim 1 wherein each of L₁ and L₂ is ##STR7## Z is CH₂ CH₂ and eachof A and B is N(CH₃)₂.
 5. A compound according to claim 1 wherein eachof L₁ and L₂ is a hexafluoroacetylacetonyl β-diketone group.
 6. Acompound according to claim 5 wherein Z is CH₂ CH₂.
 7. A compoundaccording to claim 6 wherein each of A and B is CH₃ O.
 8. A compoundaccording to claim 6 wherein A is CH₃ O and B is N(CH₃)₂.
 9. A compoundaccording to claim 6 wherein A is CH₃ S and B is N(CH₃)₂.
 10. A compoundaccording to claim 6 wherein each of A and B is SC₂ H₅.
 11. A compoundaccording to claim 6 wherein Z is C(CH₃)₂ C(CH₃)₂ and each of A and B isNH₂.
 12. A compound according to claim 1 having the structure ##STR8##wherein: R₁, R₂, R₃, and R₄ are each individually selected from C₁ to C₃perfluoroalkyl and C₁ to C₆ alkyl with at least one of R₁, R₂, R₃, andR₄ being a perfluoroalkyl group, andR₅ and R₆ are selected from hydrogenand C₁ to C₄ alkyl.
 13. A compound according to claim 12 wherein M isselected from Co and Ni.
 14. A compound according to claim 13 wherein Mis Co.
 15. A compound according to claim 13 wherein M is Ni.
 16. Acompound according to claim 12 wherein R₁, R₂, R₃, and R₄ are each CF₃.17. A compound according to claim 12 wherein R₅ and R₆ are each CH₃. 18.A compound according to claim 12 wherein Z is --C₂ H₄ --.
 19. A compoundaccording to claim 16 wherein R₅ and R₆ are each CH₃ and Z is --C₂ H₄--.
 20. A compound according to claim 14 wherein each of R₁, R₂, R₃, andR₄ is CF₃, R₅ and R₆ are each CH₃ and Z is C₂ H₄.
 21. A compoundaccording to claim 15 wherein each of R₁, R₂, R₃ and R₄ is CF₃, R₅ andR₆ are each CH₃ and Z is C₂ H₄.
 22. A compound according to claim 14wherein R₁ and R₃ are each (CH₃)₃ C, R₂ and R₄ are each CF₃, R₅ and R₆are each CH₃ and Z is C₂ H₄.
 23. A compound according to claim 14wherein R₁ and R₃ are each CF₃, R₂ and R₄ are each CH₃, R₅ and R₆ areeach CH₃ and Z is C₂ H₄.
 24. A compound according to claim 14 whereineach of R₁, R₂, R₃, and R₄ is CF₃, R₅ and R₆ are each CH₃ and Z is CH₂C(CH₃)₂ CH₂.
 25. A compound according to claim 14 wherein R₁ and R₂ areeach CH₃, R₃ and R₄ are each CF₃, R₅ and R₆ are each CH₃ and Z is C₂ H₄.26. A compound according to claim 14 wherein R₁ and R₃ are each CH₃, R₂is CH₃ CH(CH₃)CH₂, R₄ is CF₃, R₅ and R₆ are each CH₃ and Z is C₂ H₄. 27.A compound according to claim 15 wherein R₁ and R₃ are each CH₃, R₂ andR₄ are each CF₃, R₅ and R₆ are each CH₃ and Z is C₂ H₄.
 28. A compoundaccording to claim 15 wherein each of R₁, R₂, R₃ and R₄ is CF₃, R₅ andR₆ are each CH₃ and Z is CH₂ C(CH₃)₂ CH₂.
 29. A concentrate comprisingabout 5% to 50% by weight of the compound of claim 1 in an organicsolvent therefor.
 30. A fuel composition comprising a fuel boiling inthe gasoline boiling range containing an amount of a compound of claim 1to provide at least about 0.01 gram of metal per gallon of fuelcomposition.